Natural polyphenol tannic acid reinforced poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) composite films with enhanced tensile strength and fracture toughness

Novel fully biodegradable composites were successfully prepared by solution casting. The mechanical properties, chemical structure and intermolecular interaction, the melting and crystallization behaviors, and crystalline morphologies of the Tannic acid (TA)/PHBV composites were investigated. Uniaxial tensile mechanical testing results show that both tensile strength and fracture toughness were enhanced. Fourier transform infrared (FTIR) results confirm the intermolecular hydrogen bonding interactions in composites. Differential scanning calorimetric (DSC) studies show that there is a significant increase in T_g and T_cc, and a decrease in melting temperature of TA/PHBV composites. The crystal growth behaviors and crystalline morphologies results were showed that with the addition of TA component, the size of PHBV spherulites reduces, and the number of PHBV spherulites increases significantly. POLYM. COMPOS., 36:2303–2308, 2015. © 2014 Society of Plastics Engineers